We came through customs in Sydney yesterday. They did ask if we had DVD's. They asked how many. I stated we had about 50 each. Then I stated they were for personal use and not for resale up front. She asked me if they were all different titles. I said yes.
They seem to be worried about multiple copies that you will sell not your own personal use.
All was fine, she didn't even ask to look at them.
No questions about copy bags etc.